JP2006045467A - Thermoplastic resin composition and molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoplastic resin composition endowed with manufacturing stability, impact resistance and color developability, and a molded article. <P>SOLUTION: The thermoplastic resin composition comprises 30-60 pts. mass of a graft polymer (C), obtained by emulsion graft polymerization of 60-50 mass% of a monomer mixture (B) comprising an aromatic vinyl monomer and a vinyl cyanide monomer onto 40-50 mass% of a rubbery polymer (A) comprising an ethylene-propylene-non-conjugated diene copolymer and a low-molecular weight modified α-olefin copolymer and having a crosslinking degree of 70-80%, and 70-40 pts. mass of a copolymer (D) obtained by copolymerization of the aromatic vinyl monomer with the vinyl cyanide monomer, provided that the graft polymer (C) and the copolymer (D) add up to 100 pts. mass. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a thermoplastic resin composition and a molded article used for automobile exterior parts and the like.

  For example, molded articles of thermoplastic resin compositions are used for automobile exterior parts such as bumpers, door mirrors, and rear spoilers. The molded product for that purpose is required to have high impact resistance and color development, and examples of the material that satisfies the requirements include thermoplastic resins such as ABS resin, ASA resin, and polymethyl methacrylate resin. . Further, among ABS resins, a copolymer comprising an aromatic vinyl monomer, a vinyl cyanide monomer and an N-aromatic substituted maleimide, and an aromatic vinyl monomer and cyanide in the presence of a conjugated diene rubber. A heat resistant ABS resin composed of a graft polymer obtained by copolymerizing a vinyl fluoride monomer may be used.

Also, an AES resin containing a graft polymer obtained by graft polymerization of an aromatic vinyl monomer or vinyl cyanide monomer in the presence of ethylene / propylene / non-conjugated diene copolymer rubber is used. Sometimes. Since this AES resin uses an ethylene / propylene / non-conjugated diene copolymer having no double bond in the main chain as a rubber component, ultraviolet rays, oxygen and ozone are used in comparison with an ABS resin using a conjugated diene rubber. It has a high resistance to weathering, has excellent weather resistance, and is suitable for exterior parts.
As the AES resin, for example, Patent Document 1 proposes a resin containing a graft polymer obtained by emulsion graft polymerization of an aromatic vinyl monomer to an ethylene / propylene / non-conjugated diene copolymer rubber latex. Patent Documents 2 and 3 disclose emulsion graft polymerization of an aromatic vinyl monomer and a vinyl cyanide monomer with a specific production method on an ethylene / propylene / non-conjugated diene copolymer rubber latex having a specific gel fraction. The thing containing the graft polymer obtained by this is proposed (refer patent document 2, 3).
JP-A 63-291913 Japanese Patent Laid-Open No. 63-291194 Japanese Unexamined Patent Publication No. 63-291944

However, although the AES resins described in Patent Documents 1 to 3 are excellent in production stability and impact resistance, the color developability sometimes does not reach the required level. That is, the AES resins described in Patent Documents 1 to 3 did not have manufacturing stability, impact resistance, and color developability.
An object of the present invention is to provide a thermoplastic resin composition and a molded article that solves the above-described problems and has manufacturing stability, impact resistance, and color developability.

The thermoplastic resin composition of the present invention contains an ethylene / propylene / non-conjugated diene copolymer and a low molecular weight modified α-olefin copolymer, and has a rubbery polymer (A) having a crosslinking degree of 70 to 80%. Graft polymer (C) 30-60, in which 60-50% by mass of a monomer mixture (B) containing an aromatic vinyl monomer and a vinyl cyanide monomer in 40-50% by mass is emulsion graft polymerized. Part by mass;
70 to 40 parts by mass of a copolymer (D) obtained by copolymerizing an aromatic vinyl monomer and a vinyl cyanide monomer (provided that the graft polymer (C) and the copolymer (D ) Total 100 parts by mass).
The molded article of the present invention is characterized by comprising the above-described thermoplastic resin composition.

  The thermoplastic resin composition and molded product of the present invention are excellent in production stability and also in impact resistance and color development.

<Graft polymer (C)>
The graft polymer (C) is obtained by adding a rubber polymer (A) containing an ethylene / propylene / non-conjugated diene copolymer (hereinafter abbreviated as “EPDM”) and a low molecular weight modified α-olefin copolymer. The monomer mixture (B) is obtained by emulsion graft polymerization.

The rubbery polymer (A) has a crosslinking degree of 70 to 80%. When the degree of cross-linking of the rubber polymer (A) is 70 to 80%, both impact resistance and color developability can be enhanced. However, when the degree of crosslinking is less than 70%, the color developability deteriorates and it is not practical, and when it exceeds 80%, the impact resistance decreases and it is not practical.
Here, the degree of cross-linking is determined by coagulating a rubber polymer latex with dilute sulfuric acid, washing and drying with water, collecting 1 g of the dried product and immersing it in 200 ml of toluene for 40 hours, and then placing it on a 200 mesh wire mesh. The residue is dried and the mass of the dried product is measured.

  In order to adjust the degree of crosslinking of the rubber polymer (A), a method of crosslinking the uncrosslinked rubber polymer is employed. As a method for the crosslinking treatment, 0.1 to 5 parts by mass of an organic peroxide such as di-t-butyl-oxytrimethylcyclohexane and divinyl are used with respect to 100 parts by mass of the solid content of the uncrosslinked rubber polymer latex. Examples include a method in which 0.1 to 5 parts by mass of a polyfunctional compound such as benzene is added and reacted at 60 to 140 ° C. for about 0.5 to 5 hours.

 The non-conjugated diene component in the EPDM contained in the rubber polymer (A) is not particularly limited, but 1,4-hexadiene, 5-ethylidene-2-norbornene, 5-vinylnorbornene, dicyclopentadiene, and the like are preferable. .

  The rubber polymer (A) may contain a rubber component other than EPDM. Examples of rubber components other than EPDM include polybutadiene, hydrogenated polybutadiene, polyisoprene, styrene-butadiene copolymer, styrene-isoprene copolymer, butadiene-acrylonitrile copolymer, ethylene-butene-1- (non- Conjugated diene) copolymer, isobutylene-isoprene copolymer, acrylic rubber, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, SEBS and other hydrogenated diene systems (block, random and homo ) (Co) polymer, polyurethane rubber, silicone rubber and the like.

The low molecular weight-modified α-olefin copolymer is one in which the α-olefin copolymer is modified with a compound having a functional group and the mass average molecular weight is 1000 to 5000. Examples thereof include modified polyethylene obtained by copolymerization of 99.8 to 80% by mass of an α-olefin and 0.2 to 20% by mass of an unsaturated carboxylic acid compound. Here, examples of the α-olefin include ethylene, and examples of the unsaturated carboxylic acid compound include acrylic acid, maleic acid, itaconic acid, maleic anhydride, itaconic anhydride, and maleic acid monoamide.
Since the low molecular weight modified α-olefin copolymer is contained in the rubbery polymer (A), the emulsion stability can be increased, and thus the production stability is increased.

  The content of the low molecular weight modified α-olefin copolymer in the rubber polymer (A) is preferably 0.1 to 30 parts by mass with respect to 100 parts by mass of EPDM. If the content of the low molecular weight modified α-olefin copolymer is 0.1 parts by mass or more, emulsion graft polymerization can be performed more stably, but if it exceeds 30 parts by mass, the physical property balance of the obtained thermoplastic resin composition is lowered. Tend to.

  The rubbery polymer (A) preferably has an average particle size of 0.2 to 1 μm because it is excellent in the physical property balance of the resulting thermoplastic resin composition. When the average particle size is less than 0.2 μm, the impact resistance of the resulting thermoplastic resin composition may be low. When it exceeds 1 μm, the gloss tends to decrease and the surface appearance tends to deteriorate. is there.

The rubbery polymer (A) is subjected to emulsion graft polymerization in a latex state.
As a method for preparing a rubbery polymer latex, a predetermined amount of EPDM and a low molecular weight modified α-olefin copolymer is kneaded by a known melt kneading means, and sufficiently dispersed by applying a mechanical shearing force. The method of adding a thing to the aqueous medium containing an emulsifier is mentioned. According to this method, a stable rubber polymer latex can be obtained.
The melt kneading means in the latex preparation method is not particularly limited, but a kneader, a Banbury mixer, and a multi-screw extruder are preferable. Moreover, as an emulsifier, anionic surfactants, such as potassium oleate and disproportionated potassium rosinate, are used, for example. The addition amount of the emulsifier is preferably 1 to 10 parts by mass with respect to 100 parts by mass of EPDM. The emulsifier may be added by, for example, mixing oleic acid in advance with EPDM and a low molecular weight modified α-olefin copolymer, and adding potassium hydroxide aqueous solution thereto to form potassium oleate. .

[Monomer mixture (B)]
The monomer mixture (B) is a mixture containing an aromatic vinyl monomer and a vinyl cyanide monomer as essential components and another vinyl monomer polymerizable with these as an optional component.
Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, p-methylstyrene, and the like.
Examples of the vinyl cyanide monomer include acrylonitrile and methacrylonitrile.
Examples of other vinyl monomers include alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate and butyl acrylate, methyl methacrylate, ethyl methacrylate, propylene methacrylate and butyl methacrylate. Methacrylic acid alkyl ester and the like. Among these, butyl acrylate or methyl methacrylate is preferably used.
Other vinyl monomers include maleimide, N-methylmaleimide, N-butylmaleimide, N-phenylmaleimide, N- (2-methylphenyl) maleimide, N- (4-hydroxyphenyl) maleimide, N -N-substituted maleimide monomers such as cyclohexylmaleimide.

  Since the composition of the monomer compound (B) is excellent in the physical property balance of the resulting thermoplastic resin composition, the aromatic vinyl monomer is 60 to 76% by mass, and the vinyl cyanide monomer is 40 to 40%. The content is preferably 24% by mass, and other vinyl monomers are 0 to 20% by mass.

[Production method of graft polymer (C)]
Examples of the method for producing the graft polymer (C) include a method in which the monomer mixture (B) is added to the latex of the rubber-like polymer (A), and the emulsion is subjected to emulsion graft polymerization by heating to a predetermined polymerization temperature. . In particular, the monomer mixture (B) may be continuously added to the latex of the rubbery polymer (A) over a period of 1 hour or more after mixing the redox initiator with the monomer mixture (B). preferable. When the addition time of the monomer mixture (B) is less than 1 hour, the latex stability may be lowered and the polymerization yield may be lowered.
You may add antioxidant to the graft polymer (C) after superposition | polymerization as needed.

  The redox initiator used here is preferably a combination of an oil-soluble organic peroxide and a ferrous sulfate-chelating agent-reducing agent. Examples of the oil-soluble organic peroxide include cumene hydroperoxide, diisopropylbenzene hydroperoxide, and tertiary butyl hydroperoxide. More preferred redox initiators include cumene hydroperoxide, ferrous sulfate, sodium pyrophosphate, and dextrose.

  In the graft polymer (C), 60 to 50% by mass of the monomer mixture (B) is polymerized to 40 to 50% by mass (as a solid content) of the rubbery polymer (A) ((A) and (B). ) 100 mass%). When the rubber polymer (A) is less than 40% by mass (monomer mixture exceeds 60% by mass), the impact resistance is lowered, and the rubber polymer (A) exceeds 80% by mass (single amount). When the body mixture is less than 20% by mass), the color developability is lowered.

  A graft polymer latex is obtained by the above-described method for producing a graft polymer. As a method for recovering the graft polymer (C) from the graft polymer latex, for example, a precipitant is added to the graft polymer latex, and after heating and stirring, the precipitant is separated, washed with water, dehydrated and dried. A precipitation method is employed. As the precipitation agent in the precipitation method, for example, an aqueous solution of sulfuric acid, acetic acid, calcium chloride, magnesium sulfate, or the like can be used alone or in combination.

<Copolymer (D)>
The copolymer (D) is a copolymer of an aromatic vinyl monomer and a vinyl cyanide monomer. Further, the copolymer (D) may be copolymerized with other vinyl monomers copolymerizable with the aromatic vinyl monomer and the vinyl cyanide monomer.
Specific examples of the aromatic vinyl monomer, vinyl cyanide monomer, and other vinyl monomers include the same as the monomer mixture (B).
The composition of the copolymer (D) is not particularly limited, but is 60 to 76% by weight of an aromatic vinyl monomer, 40 to 24% by weight of a vinyl cyanide monomer, and copolymerized with these monomers. Those containing 0-20% by weight of possible monomers are preferred.

For the production of the copolymer (D), a polymerization method such as emulsion polymerization or suspension polymerization is employed. When the copolymer (D) is produced by emulsion polymerization, each monomer, an emulsifier, a polymerization initiator, and a chain transfer agent are charged into the reactor and polymerized by heating. From the obtained copolymer latex The copolymer (D) is recovered by a precipitation method.
Here, general emulsifiers for emulsion polymerization such as potassium rosinate and sodium alkylbenzenesulfonate can be used as the emulsifier. Moreover, organic and inorganic peroxide initiators can be used as the polymerization initiator, and mercaptans, α-methylstyrene dimers, terpenes, and the like can be used as the chain transfer agent. As the precipitation method, a method similar to the method of recovering the graft polymer (C) from the graft polymer latex can be employed.

In the case of producing by suspension polymerization, each monomer, suspending agent, suspending aid, polymerization initiator and chain transfer agent are charged into the reactor and polymerized by heating to obtain a copolymer slurry. And the copolymer (D) is recovered.
Here, as the suspending agent, tricalcium phosphite, polyvinyl alcohol or the like can be used, and as the suspending aid, sodium alkylbenzene sulfonate or the like can be used. Further, organic peroxides can be used as the polymerization initiator, and mercaptans, α-methylstyrene dimer, terpenes, and the like can be used as the chain transfer agent.

<Thermoplastic resin composition>
Since the thermoplastic resin composition has a good balance between color developability and impact resistance, the graft polymer (C) described above with respect to a total of 100 parts by mass of the graft polymer (C) and the copolymer (D). Is 30 to 60 parts by mass and the copolymer (D) is 70 to 40 parts by mass, and the graft polymer (C) is 35 to 50 parts by mass and the copolymer (D). It is preferable that content of is 65-50 mass parts. When the content of the graft polymer (C) is less than 30 parts by mass (the content of the copolymer (D) exceeds 70 parts by mass), the impact resistance becomes low, and the content of the graft polymer (C) When the amount exceeds 60 parts by mass (the content of the copolymer (D) is less than 30 parts by mass), the color developability is lowered.

  The thermoplastic resin composition is prepared by mixing the graft polymer (C) and the copolymer (D) with additives such as an antioxidant, a lubricant, a processing aid, a pigment, and a filler, if necessary. For example, it can be easily produced by pelletizing with an extruder, a Banbury mixer or a kneading roll.

  Since this thermoplastic resin composition has a high color developability, it is suitable for coloring. When the thermoplastic resin composition is colored, for example, a colorant such as a color pigment, dye, carbon black, or titanium oxide is used as an additive.

<Molded product>
Next, the molded product of the present invention will be described. The molded article of the present invention is obtained by molding the above-described thermoplastic resin composition. Examples of the molding method include an injection molding method, a press molding method, an extrusion molding method, a vacuum molding method, and a blow molding method.
The molded article of the present invention is suitable for automotive exterior parts such as bumpers, door mirrors, rear spoilers, etc., but can also be applied to other uses.

  EXAMPLES Hereinafter, although a manufacture example, an Example, and a comparative example are given and this invention is demonstrated further more concretely, unless this summary is exceeded, this invention is not limited to a following example. In the following, “part” means “part by mass” and “%” means “mass%”.

"Production Example 1" Production of rubbery polymer (A-1)
90 parts of EPDM (TP3180 manufactured by Mitsui Chemicals), 10 parts of low molecular weight modified polyethylene (High Wax 2203A manufactured by Mitsui Chemicals), and 5 parts of potassium oleate were mixed. Then, the mixture was supplied at 4 kg / hour from the hopper of a twin screw extruder (Ikegai Steel Co., Ltd. PCM-30 type, L / D = 40), and a potassium hydroxide 15% aqueous solution was supplied at 110 g / hour. While continuously feeding, the melt was kneaded at a heating temperature of 180 ° C. to extrude the melt. Subsequently, the melt was continuously supplied to a cooling single screw extruder attached to the tip of the extruder and cooled to 90 ° C. The taken-out solid was poured into warm water at 80 ° C. and continuously dispersed to obtain a rubber polymer latex having an average particle size of 0.45 μm.

To 100 parts of this latex, 2.0 parts of di-t-butylperoxytrimethylcyclohexane and 2.0 parts of divinylbenzene were added and reacted at 120 ° C. for 1 hour to give a rubbery polymer (A -1) was prepared.
The degree of cross-linking of this rubber polymer (A-1) was measured and found to be 74%. The degree of crosslinking was determined by coagulating the rubber polymer latex with dilute sulfuric acid, washing with water and drying, collecting 1 g of this, immersing it in 200 ml of toluene for 40 hours, and then filtering with a 200 mesh wire mesh. The residue was dried and measured for its mass.

"Production Example 2"
A rubbery polymer (A-2) was prepared in the same manner as in Production Example 1 except that the addition amount of di-t-butylperoxytrimethylcyclohexane was 3.0 parts and the addition amount of divinylbenzene was 2.0 parts. Prepared. The degree of crosslinking of the rubber polymer (A-2) was 93%.
"Production Example 3"
A rubbery polymer (A-3) was prepared in the same manner as in Production Example 1 except that the addition amount of di-t-butylperoxytrimethylcyclohexane was 1.0 part and the addition amount of divinylbenzene was 2.0 parts. Prepared. The degree of crosslinking of the rubber polymer (A-3) was 62%.

“Production Example 4” Graft polymer production method (C-1)
In a stainless polymerization tank equipped with a stirrer, 200 parts of ion-exchanged water, 45 parts of rubber polymer (A-1) as solids, 2 parts of potassium oleate, 0.004 part of ferrous sulfate, 0.2 parts of sodium pyrophosphate And 0.2 part of dextrose were charged, and the temperature was set to 80 ° C. Next, 1.85 parts of acrylonitrile and 3.65 parts of styrene were charged into the polymerization tank and stirred at 80 ° C. for 30 minutes. Next, a monomer mixture consisting of 16.75 parts of acrylonitrile and 32.75 parts of styrene and 0.6 part of cumene hydroperoxide are continuously added for 2 hours, and the emulsion temperature is kept constant at 80 ° C. by emulsion graft polymerization. Went. The monomer conversion after the polymerization was 95%.
After the polymerization, an antioxidant is added to the obtained graft polymer latex, solid content is precipitated with sulfuric acid, and after washing, dehydration and drying, the powdered graft polymer (C-1) is obtained. Obtained.

"Production Example 5"
A graft copolymer (C-2) was obtained in the same manner as in Production Example 4 except that the rubber polymer (A-2) was used instead of the rubber polymer (A-1).
"Production Example 6"
A graft copolymer (C-3) was obtained in the same manner as in Production Example 4 except that the rubber polymer (A-3) was used instead of the rubber polymer (A-1).
"Production Example 7"
Same as Production Example 4 except that the amount of rubber polymer (A-1) was 60 parts, the amount of acrylonitrile added was 13.6 parts, and the amount of styrene added was 26.4 parts (total 40 parts). Thus, a graft copolymer (C-4) was obtained.
In addition, in Table 1, the kind and quantity of the rubber-like polymer in manufacture examples 4-7, and the quantity of a monomer mixture are shown.

“Production Example 8” Copolymer Production Method (D)
In a stainless steel polymerization reactor equipped with a stirrer substituted with nitrogen, 120 parts of ion exchange water, 0.1 part of polyvinyl alcohol, 0.3 part of azobisisobutyronitrile, 34 parts of acrylonitrile, 66 parts of styrene, t-dodecyl mercaptan 0 .3 parts were charged. The reactor was heated to 50 ° C. for 5 hours, heated to 120 ° C., polymerized for 4 hours, and then extracted to obtain a copolymer (D). The monomer conversion in the polymerization was 98%, and the mass average molecular weight of the obtained copolymer (D) was 1.0 × 10 ⁵ .

(Examples 1 and 2 and Comparative Examples 1 to 4)
Each component obtained by the method described above was mixed in the formulation shown in Table 2, and the mixture was melt-kneaded with an extruder to obtain a thermoplastic resin composition. As carbon black, Mitsubishi Carbon Black # 1000B manufactured by Mitsubishi Chemical Corporation was used.

The mechanical strength, impact resistance, and color developability of the obtained thermoplastic resin composition were evaluated as follows. The evaluation results are shown in Table 2.
Mechanical strength: Using Toshiba Machine's injection molding machine IS55FP-1.5A, a test piece was prepared according to ISO 3167, and the bending strength was measured according to the method of ISO 178.
Impact resistance: Using Toshiba Machine's injection molding machine IS55FP-1.5A, a test piece was prepared according to ISO 3167 and measured according to the method of ISO 179.
Color developability: L * (brightness) of the surface of the test piece was measured according to JIS Z8729. In addition, it shows that color development is so good that L * is low.

  In Examples 1 and 2 satisfying the scope of claim 1 of the present application, both impact resistance and color development were high. On the other hand, Comparative Example 1 in which the degree of crosslinking of the rubber polymer exceeded 80% had low impact resistance, and Comparative Example 2 in which the degree of crosslinking of the rubber polymer was less than 70% had low color development. Further, Comparative Example 3 in which the amount of the rubber-like polymer in the graft copolymer exceeded 50% had low impact resistance and color developability. Further, Comparative Example 4 in which the blending amount of the graft copolymer was less than 30 parts had low impact resistance.

Claims (2)

The rubbery polymer (A) containing an ethylene / propylene / non-conjugated diene copolymer and a low molecular weight modified α-olefin copolymer and having a crosslinking degree of 70 to 80% is mixed with 40 to 50% by mass of aromatic vinyl. 30-60 parts by mass of a graft polymer (C) obtained by emulsion graft polymerization of 60-50% by mass of a monomer mixture (B) containing a monomer and a vinyl cyanide monomer;
70 to 40 parts by mass of a copolymer (D) obtained by copolymerizing an aromatic vinyl monomer and a vinyl cyanide monomer (provided that the graft polymer (C) and the copolymer (D ) In total 100 parts by mass).   A molded article comprising the thermoplastic resin composition according to claim 1.